The role of soluble factors (lymphokines) released from stimulated lymphocytes will be studied for their role in facilitating the generation of cytotoxic lymphocytes in vitro and in vivo. In vitro, soluble factors will be examined in a mixed leukocyte reaction that has been compromised by treating the stimulating cells with U.V., glutaraldehyde or heat, and the development of cytotoxic T cells measured. We also will study the effects of soluble factors on the generation of cytotoxic lymphocytes to malignant melanoma in vitro. In vivo we will continue to explore the mechanism by which lymphokines injected into nodules of metastatic melanoma lead to the development of a mononuclear cell infiltrate and the frequent regression of noninjected metastatic nodules as well as the injected nodules.